1. Field of the Invention
This invention concerns compositions for ingestion by animals. More particularly, though not exclusively, the present invention concerns the use of microorganisms of the genus Propionibacterium, in reducing nitrate intoxication of ruminants.
2. Brief Description of the Related Art
Ruminant intoxication by nitrates present in forages has been recognized for at least 100 Years. Nitrates are ubiquitous in feed and water and are essentially nontoxic. Nitrates become toxic when reduced to nitrites. Ruminants that consume a high nitrate diet have been reported to adapt and reduce nitrate to nitrite more rapidly due to selection and induction of microbial nitrate reduction activity. As nitrate reduction increases, the rate of nitrate reduction to nitrite exceeds the rate of nitrite reduction to ammonia, resulting in accumulation of toxic levels of nitrite. Nitrite is absorbed into the blood where it converts blood hemoglobin to methemoglobin (heme iron is oxidized from ferrous to ferric form) resulting in a loss of the oxygen transporting capacity of the blood and anoxia of the animal. The resulting characteristic symptom is a chocolate-brown colour to the blood.
Several techniques have been used to control the incidence of nitrate poisoning. Plant management practices such as reducing nitrogen fertilization rates and practicing certain harvest strategies such as cutting stalks 12 to 18 inches (30 to 45 cm) above the ground at full plant maturity and never immediately following rain; help to reduce the amount of nitrate in forage crops but do not eliminate nitrate accumulated in the plant material. Animal management strategies include feeding practices such as diluting high nitrate forages with feed low in nitrate, feeding high nitrate feed gradually to allow for adaption of the ruminal microbes and supplementing diets of high nitrate feed with grain. Although these management practices help reduce the effect of high nitrate feed, young animals or nutritionally stressed animals are more susceptible to nitrate toxicity and may not be protected. In addition, high nitrate diets can reduce feed intake resulting in reduced performance.
The feeding of specific viable microorganisms to livestock with the intent to alter the microbial balance within the gastrointestinal tract has been in practice for many years. Although the mode of action of these direct-fed microbial products and their beneficial effect has not always been scientifically demonstrated, the important role microorganisms play in fermentation and digestion is well recognized. Currently there are no microorganisms fed to livestock for the purpose of reducing nitrate toxicity.
Accordingly, it is the primary objective of the present invention to develop a composition containing microorganisms which when fed to livestock will reduce the effects of nitrate toxicity.